In the past decade, researchers have combined evolutionary theory and molecular biology to uncover the profound and complex ways in which male organisms manipulate the behavior and physiology of females after mating. Because females pay a fitness cost while males gain from manipulating, females should evolve defenses. However, nothing is known about the nature of such female mechanisms, despite mounting evidence that they exist. The long term goal is to open this female black box by determining female-specific genes expressed in response to mating, distinguish the subset of those genes that are probable candidates for a defensive role, and to elucidate the function(s) of their gene products. Evidence suggests that females in many taxa can produce unique anti-bacterial proteins, possibly to defend against transmission of sexually transmitted diseases (STDs). The proposed research will take an important step in determining how widespread the production of anti-bacterial and anti- STD is among organisms, including vertebrates. The aims of the proposed project are to test the following hypotheses: (i) that the reproductive accessory glands of female fruit flies produce compounds that are unique to females; and (ii) that the synthesis of some accessory gland components increases significantly after mating. Most importantly, the project is designed to identify female-specific genes which respond to the presence of sperm or male ejaculatory products. These goals will be reached by using microarrays to assay gene expression in virgin vs. mated females, as well as females mated to wild type mates vs. females mated to sterile males.